Personally I superset squats and standing calf raises (same bar). 20 reps squats. 20 reps raises. I no longer go over 2 plates due to the volume. It's also the second superset that I do after extensions and hamstring curls (again 20 rep sets).

I have done over 5 1/2 plates for 11 reps but it was fucking hard on me. Stopped going so heavy after that, did do 20's on 4 plates a side for a while but now i would squat 2 and then on the smith if i squatted. There's no point to doing 4, you work the nervous system too much and not the muscle.

Or maybe as you have trained for longer you can get more out of the muscle doing any kind of weights which is very true. I do 4 now i would feel it so fucking much, where as doing it when i was only training a few years didn't do that, and it's not age.

Kai does 5 plates with no problem. Saw him do a set with 6 somewhere. Roelly was doind like 650 lbs for reps fairly recently. I believe Jason Huh squats some ridiculous weights as well. Strangely enough, these guys are some of the thickest and most muscular pros going. I think the OP is thinking Phil Heath - who doesnt go very heavy- but he would grow doing Shake weight .